AND vs as operator

Question

I have a codebase where developers decided to use AND and OR instead of  amp  amp  and      I know that there is a difference in operators  precedence   amp  amp  goes before and   but with the given framework  PrestaShop to be precise  it is clearly not a reason   Which version are you using  Is and more readable than  amp  amp   Or is there no difference

User · Answer

Since and has lower precedence than   you can use it in condition assignment   if   var   true  amp  amp  false     Compare true with false and assign to  var if   var   true and false     Assign true to  var and compare  var to false

User · Answer

Here s a little counter example    a   true   b   true   c    a  amp   b  var dump true      c     output   bool false    I d say this kind of typo is far more likely to cause insidious problems  in much the same way as   vs     and is far less likely to be noticed than adn ro typos which will flag as syntax errors  I also find and or is much easier to read  FWIW  most PHP frameworks that express a preference  most don t  specify and or  I ve also never run into a real  non-contrived case where it would have mattered

User · Answer

which version are you using    If the coding standards for the particular codebase I am writing code for specifies which operator should be used  I ll definitely use that  If not  and the code dictates which should be used  not often  can be easily worked around  then I ll use that  Otherwise  probably  amp  amp       Is  and  more readable than   amp  amp      Is it more readable to you  The answer is yes and no depending on many factors including the code around the operator and indeed the person reading it         there is   difference    Yes  See logical operators for    and bitwise operators for

User · Answer

If you use AND and OR  you ll eventually get tripped up by something like this    this one   true   that   false    truthiness    this one and  that    Want to guess what  truthiness equals   If you said false    bzzzt  sorry  wrong    truthiness above has the value true   Why     has a higher precedence than and  The addition of parentheses to show the implicit order makes this clearer     truthiness    this one  and  that   If you used  amp  amp  instead of and in the first code example  it would work as expected and be false   As discussed in the comments below  this also works to get the correct value  as parentheses have higher precedence than      truthiness     this one and  that

User · Answer

Precedence differs between  amp  amp  and and   amp  amp  has higher precedence than and   something that causes confusion when combined with a ternary operator  For instance    predA  amp  amp   predB    foo     bar    will return a string whereas   predA and  predB    foo     bar    will return a boolean

User · Answer

Another nice example using if statements without   assignment operations   if  true    true  amp  amp  false      is the same as  if  true     true  amp  amp  false       TRUE   and  if  true    true AND false      is the same as  if   true    true   amp  amp  false      FALSE   because AND has a lower precedence and thus    a higher precedence   These are different in the cases of true  false  false and true  true  false  See https   ideone com lsqovs for en elaborate example

User · Answer

For safety  I always parenthesise my comparisons and space them out  That way  I don t have to rely on operator precedence   if         i  0   amp  amp   b  2                  c  3   amp  amp    f  5

User · Answer

Depending on how it s being used  it might be necessary and even handy  http   php net manual en language operators logical php          has a greater precedence than  or      The result of the expression  false    true  is assigned to  e    Acts like    e    false    true    e   false    true      The constant false is assigned to  f and then true is ignored    Acts like     f   false  or true   f   false or true    But in most cases it seems like more of a developer taste thing  like every occurrence of this that I ve seen in CodeIgniter framework like  Sarfraz has mentioned

User · Answer

I guess it s a matter of taste  although  mistakenly  mixing them up might cause some undesired behaviors   true  amp  amp  false    false     returns false  true and false    false     returns true   Hence  using  amp  amp  and    is safer for they have the highest precedence  In what regards to readability  I d say these operators are universal enough   UPDATE  About the comments saying that both operations return false     well  in fact the code above does not return anything  I m sorry for the ambiguity  To clarify  the behavior in the second case depends on how the result of the operation is used  Observe how the precedence of operators comes into play here   var dump true and false    false      bool false    a   true and false    false  var dump  a      bool true    The reason why  a     true is because the assignment operator has precedence over any logical operator  as already very well explained in other answers

User · Answer

Let me explain the difference between    and    -     amp  amp     -   amp        amp  amp   and  and  both are logical AND operations and they do the same thing  but the operator precedence is different   The precedence  priority  of an operator specifies how  tightly  it binds two expressions together  For example  in the expression 1   5   3  the answer is 16 and not 18 because the multiplication       operator has a higher precedence than the addition       operator   Mixing them together in single operation  could give you unexpected results in some cases I recommend always using  amp  amp   but that s your choice     On the other hand   amp   is a bitwise AND operation  It s used for the evaluation and manipulation of specific bits within the integer value   Example if you do  14  amp  7  the result would be 6   7     0111 14    1110 ------------       0110    6

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